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python解决字典中的值是列表问题的方法

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Release： 2016-06-16 08:46:47
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问题：查找一些英文词在哪些小句中出现了，当然是用python来实现，当然是用字典，但是怎么让一个key对应一个 类型为列表的value，直接用列表的append()是不行的，比如dic[key].append(value)，因为解释器并不知道 dic[key]的类型，当时赶时间，用了一个折衷的方案，就是先用value连成一个str，最后用str.split()作一个转换，生成一个列表.

    看了python cookbook，上面正好有一个recipe讲到如何处理这样的问题，好了，揭晓答案吧!

(1)value中允许有重复项.

复制代码 代码如下:

dic = {}
dic.setdefault(key，[]).append(value)
#如:
d1.setdefault('bob_hu'，[]).append(1)
d1.setdefault('bob_hu'，[]).append(2)
print d1['bob_hu'] # [1，2]

(2)value中无重复项.

复制代码 代码如下:

dic = {}
dic.setdefault(key，{})[value] = 1
#如:
d1.setdefault('bob'，{})['f'] = 1
d1.setdefault('bob'，{})['h'] = 1
d1.setdefault('bob'，{})['f'] = 1
print d1['bob'] #{'h': 1， 'f': 1}
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